Check that it works with Klipper!
The convenience and control Klipper provides is phenomenal. You don’t have to use it if it turns out you dont like it, but I feel like ruling it out as an option now would be a shame.
I would also point out that you should not be put off by the “official” supported printers list for Klipper, a bit of Googling will often turn up some mini projects where people are actively working on supporting the printer with Klipper before the main project gets round to adding official support.
This works very well with OpenWRT on each AP and/or router device by using the same ESSID and password combo on each of them, enabling WLAN roaming and also 802.11r Fast Transition to allow your mobile devices to hand-off quickly from one AP to another as signal strength levels demand. With this enabled you keep the same IP address, and even SSH sessions don’t drop when you move from one AP to another, it all happens in the background. As far as the end-user is concerned it is all just one big happy wifi network.
802.11r is not mesh, that’s a separate thing but and you can do it with OpenWRT too. I don’t need to because I have ethernet to all my APs, so all the RF bandwidth is available for the last leg from AP to device(s), and not being used by back-haul from AP to AP through to the router as well.
In your use case I would consider grouping devices into categories and having a different wifi network for each category with the dhcp and firewall rules set accordingly.
VLANs on the ethernet-side might also be useful, but it sounds like most of your devices are on WiFi, so it might well be possible to get a “mature” setup without needing that extra complexity.
As others have said, backing these settings up and restoring them to a new device in the case of hardware failure is generally straightforward. Care is needed when replacing the broken device with a new one because of naming conventions varying from device to device, but the network logic, and things like dhcp reservations can be carried over.